Land management shapes drought responses of dominant soil microbial taxa across grasslands.

Soil microbial communities are dominated by a relatively small number of taxa that may play outsized roles in ecosystem functioning, yet little is known about their capacities to resist and recover from climate extremes such as drought, or how environmental context mediates those responses. Here, we imposed an in situ experimental drought across 30 diverse UK grassland sites with contrasting management intensities and found that: (1) the majority of dominant bacterial (85%) and fungal (89%) taxa exhibit resistant or opportunistic drought strategies, possibly contributing to their ubiquity and dominance across sites; and (2) intensive grassland management decreases the proportion of drought-sensitive and non-resilient dominant bacteria-likely via alleviation of nutrient limitation and pH-related stress under fertilisation and liming-but has the opposite impact on dominant fungi. Our results suggest a potential mechanism by which intensive management promotes bacteria over fungi under drought with implications for soil functioning.

High-resolution characterization of short-term temporal variability in the taxonomic and resistome composition of wastewater influent.

Wastewater-based epidemiology (WBE) for population-level surveillance of antimicrobial resistance (AMR) is gaining significant traction, but the impact of wastewater sampling methods on results is unclear. In this study, we characterized taxonomic and resistome differences between single-timepoint-grab and 24 h composites of wastewater influent from a large UK-based wastewater treatment work [WWTW (population equivalent: 223 435)]. We autosampled hourly influent grab samples (n=72) over three consecutive weekdays, and prepared additional 24 h composites (n=3) from respective grabs. For taxonomic profiling, metagenomic DNA was extracted from all samples and 16S rRNA gene sequencing was performed. One composite and six grabs from day 1 underwent metagenomic sequencing for metagenomic dissimilarity estimation and resistome profiling. Taxonomic abundances of phyla varied significantly across hourly grab samples but followed a repeating diurnal pattern for all 3 days. Hierarchical clustering grouped grab samples into four time periods dissimilar in both 16S rRNA gene-based profiles and metagenomic distances. 24H-composites resembled mean daily phyla abundances and showed low variability of taxonomic profiles. Of the 122 AMR gene families (AGFs) identified across all day 1 samples, single grab samples identified a median of six (IQR: 5-8) AGFs not seen in the composite. However, 36/36 of these hits were at lateral coverage <0.5 (median: 0.19; interquartile range: 0.16-0.22) and potential false positives. Conversely, the 24H-composite identified three AGFs not seen in any grab with higher lateral coverage (0.82; 0.55-0.84). Additionally, several clinically significant human AGFs (bla VIM, bla IMP, bla KPC) were intermittently or completely missed by grab sampling but captured by the 24 h composite. Wastewater influent undergoes significant taxonomic and resistome changes on short timescales potentially affecting interpretation of results based on sampling strategy. Grab samples are more convenient and potentially capture low-prevalence/transient targets but are less comprehensive and temporally variable. Therefore, we recommend 24H-composite sampling where feasible. Further validation and optimization of WBE methods is vital for its development into a robust AMR surveillance approach.

Confirmation of the species status of the blackfly Simulium galeratum in Britain using molecular taxonomy.

Since 1920 Simulium reptans (Linnaeus) (Diptera: Simuliidae) has been reported as exhibiting two different larval morphotypes, a typical S. reptans and an atypical S. reptans var. galeratum, which differ in the markings of the larval head capsule. Inconsistent variation in adults and no apparent variation in the pupae have led taxonomists to conclude that these types in Britain are a single species. We investigated populations in Britain where either the typical form or var. galeratum is found, and one population where the two exist sympatrically. A phylogenetic study based upon a region of the mitochondrial cytochrome c oxidase 1 gene (DNA barcoding) produced a tree that delineated the morphotypes into two distinct monophyletic clades. The average Kimura-2-parameter distances within each clade (i.e. within each morphotype) were very low (0.67% and 0.78%), with the distances between morphotypes being 9-10-fold greater (mean 7.06%). This is concordant with differences within and between species in other taxa; based upon the strict correlation between the molecular variation and the morphotypes, we propose the re-instatement of S. galeratum to species status.

FK506-induced endothelin release by cultured rat mesangial cells.

Renal damage is a major side effect of the macrolide immunosuppressant FK 506. Although little is known about the underlying mechanism of FK 506 nephrotoxicity, available data suggest that it may be associated with a disturbance in renal hemodynamics, possibly brought about by alterations in the production of vasoactive substances such as endothelin-1 (ET-1). We have investigated the release of ET-1 from primary renal mesangial cells in culture. Mesangial cells derived from rat renal cortex were exposed to a range of FK 506 concentrations (10(-10) to 10(-6) M) or vehicle for up to 6 h. FK 506 caused a significant dose-related increase in ET release. This effect was dependent on cell density and was blocked by co-incubation with FPL 65620, an FK 506 analogue that binds to the FK binding protein (FKBP) and inhibits the immunosuppressive activity of FK 506. These data suggest that mesangial cell ET may play a role in FK 506 nephrotoxicity and that the effect of FK 506 on ET release may be mediated through the FKBP.

Effect of melanocyte stimulating hormone on human cultured choroidal melanocytes, uveal melanoma cells, and retinal epithelial cells.

PURPOSE: To establish methodology for the culture of human choroidal melanocytes to compare their responsiveness to melanocyte stimulating hormone (MSH) with that of their transformed melanoma counterparts and with that of the retinal epithelial cell. METHODS: Choroidal melanocytes from the choroid of eyes enucleated for the presence of malignant melanoma were cultured in MCDB 153 medium supplemented with insulin, transferrin, hydrocortisone, glutamine, nystatin, vitamin E, phorbol myristate acetate, bovine hypothalamic extract, cholera toxin, and chelexed fetal calf serum. RESULTS: High yields of pure spindle-shaped bipolar melanocytes were obtained with a doubling time of 3 to 4 days in nine consecutive eyes. Cells continued to divide after 4 months in culture. In contrast, uveal malignant melanoma cells grew rapidly in a relatively simple medium of Ham's F12:DMEM (1:1) supplemented with fetal calf serum, insulin, transferrin and glutamine. This medium was unable to support choroidal melanocytes. Choroidal melanocytes were DOPA-positive with appreciable tyrosinase activity that significantly increased with treatment with MSH. MSH also significantly altered the size, local density, and distribution of primary and mature melanosomes of ocular melanocytes. In contrast, uveal melanoma cells had a low level of tyrosinase activity and failed to respond to MSH with either an increase in enzyme activity or melanosome size. Retinal epithelial cells failed to show significant tyrosinase activity under the conditions studied or any increase in melanosome size in response to MSH. CONCLUSION: Ocular melanocytes show evidence of regulation by MSH and a range of mitogenic stimuli unlike the transformed melanoma cells, implying a loss of regulatory control in the latter.

Inhibition of melanoma cell/matrix interaction by tamoxifen.

Following our recent finding that calmodulin antagonists can reduce cancer cell attachment to extracellular matrix proteins, we investigated the calmodulin antagonistic and anti-attachment properties of the non-steroidal anti-oestrogens tamoxifen and droloxifene. These drugs and four of their active metabolites were found to have calmodulin antagonist activity with IC50 values of 2-4 microM and to be capable of inhibiting attachment of murine B16 melanoma to extracellular matrix proteins in vitro. IC50 values for inhibition of attachment were 11 microM for tamoxifen and ranged from 5 to 40 microM for the other five compounds tested. (Poor reproducibility in drug potency between attachment experiments was almost certainly due to the low aqueous solubility of these drugs.) The effects of tamoxifen on cell/matrix adhesion were most evident between 15 min and 3 h of cell attachment. No effects of tamoxifen were evident in cells which had been allowed to attach for 6 h or more. Tamoxifen at concentrations between 0.1 and 30 microM was without effect on intracellular free calcium concentration. Tamoxifen also inhibited attachment of human ocular melanoma cells and human breast cancer (MCF7) cells to type I collagen. The concentration at which tamoxifen and its metabolites affect cell attachment in vitro (2-14 microM) is of the same order as the tissue concentrations of these drugs achieved clinically. The possibility exists that reduction of cell/matrix interactions may contribute to the clinical anti-metastatic efficacy of tamoxifen and some of its active metabolites.

Self-management of diabetes mellitus: a critical review.

Diabetes has no known cure and is a leading source of morbidity and mortality. Clinical management involves patients managing a complex and variable regimen. This article reviews the determinants of effective self-management and the methods of promoting better self-management. Trait variables (e.g., personality and demographics) have been presumed to affect self-management, but evidence suggests they have little impact. The important determinants of self-management are transient situational factors such as psychological stress and social pressure to eat. Interventions to promote better self-management have reported initial improvements in blood glucose control, but the long-term effects are unclear. We conclude that self-management has been inadequately assessed and that attempts to improve self-management have relied excessively on providing information. More research is needed to clarify determinants of self-management, and interventions to improve self-management will need to change these determinants.

The metallography of heat treatment effects in a nickel-base casting alloy. A preliminary report.

A series of standard tensile specimens produced from a nickel-base removable partial denture casting alloy were subjected to heat treatments at three temperatures and three periods at each temperature. The microstructures developed within the castings disclose changes in both the matrix and interdendritic zones.

Duplication variables related to partial denture castings. 1. The duplicating flask.

A metal die simulating a model of a partially dentate upper jaw prepared with milled facets for reference measurement with vernier calipers was used for the making of duplicate stone models, in three different duplicating flasks. The observation showed that irrespective of the flask size, the duplicated models were slightly wider.

A stucy of duplication variables related to partial denture castings.

A series of stone duplications of a standard impression die was produced, using a proprietary duplicating material, the various batches of which had been prepared differently. Two different sized duplicating vessels were also employed. The critical dimensions of the stone reproductions were compared with those of the original die. Specimens of each batch of duplicating material were tested to determine the degree of permanent deformation produced by a fixed strain and strain in compression.